straited glutes is a good indicator of general level of shreddness. it's like saying "look at me, im so sliced and diced EVEN the glutes are shredded!"
It is also a great way to say, "I'm gay. Come pound my ass."
I agree with the others. Who gives a shit about striated glutes? If the competitor is shredded, it will be apparent without showing the glutes. It is just another way that bodybuilding gives the mainstream a message that says, "Bodybuilding is gay".